Method of treating ferruginous zinc-chlorid solutions.



ICE.

' sTAnLET' HERBERT LAWTON, or WILMINGTON, DELAWARE, ASSIGNOR To AMERICANVU' LCA NIZED FIBRE COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION" 0DELAWARE.

' METHoD or TREATING TERRUerNoUs ZINC-GHLORID SOLUTIONS.

No Drawing.

To all/whom itmay concern siding at Wilmingtom'in the county of NewCastle and State of Delaware, have invented certain new and usefulImprovements in Methods of Treating Ferruginous Zinc- Chlorid Solutions,of which the following is a specification.

This invention relates to the treatment of iron-bearing zinc chloridsolutions, such as are obtained for example by the treatment ofgalvanized scrap by hydrochloric acid, or from other sources, one objectof the invention being to prepare therefrom commercially pure zincchlorid, the iron being separated in the form of anhydrous ferric oxid.

The invention likewise relates broadly to the dehydration of ferricsalts or compounds by zinc chlorid.

In practising the invention, advantage is taken of the heretoforeunobserved fact that highly-concentrated solutions 0 zinc chlorid arecapable, under certain conditions, of de-' hydrating ferric compounds,as ferric hydroxid, with formation of anhydrous ferric oxid. r 1

According to the invention, as applied to the purification of zincchlorid solutions, the ferruginous zinc chlorid solution from any sourcereceives, either before or during concentration, any suitable basicaddition, in quantity approximately proportionate to the ferric saltpresent. In case the iron'is originally present in the ferrous state, itis preliminarily converted into the ferric condition by any suitablemethods, as for example by treatment with nitric acid, chlorin,

zinc nitrate or the like. The basic addition referred to is preferably azinc compound or basic character, as the oxid, carbonate,

' basic chlorid or the like, the purpose of the addition being to effectthe immediate or ultimate precipitation of the, ferric iron in oxidizedform (hydroxid or oxid). The liquor is concentrated tosuch: degree, andunder such conditions, that the iron is ulti mately thrown out, underthe dehydrating action of the zinc chlorid, in the form of an hydrousferric oxid.

Specification of Letters Patent.

of zinc present.

open pans or in cacao.

Patented May 4, 1915.

Application filed June 21, 1913. Serial No. 775,100.

In case the proportion of iron in the'original solution is relativelysmall, say not in excess of about one percent. of the zinc present, adirect addition of basic compound is usually unnecessary for the reasonthat the loss of hydrochloric acid during the concentration will resultin the formation of a corresponding proportion of zinc oxid or otherbasic zinc compounds, which will suffice for the precipitation of smallproportions of iron. Where larger proportions of iron are present, orwhere the conditions of the concentration are such that very littledecomposition of the zinc chlorid occurs,

the basic addition is made directly to'the solution.

In quantity the basic addition may be chemically equivalent to theferric iron present, but in such case the resulting purified zincchlorid will usually be somewhatbasic in character, owingto theabove-mentioned decomposition during concentration. The

.isfactoryto make the basic addition chemically equivalentto the excessof ferric iron above one per cent, basedyupon the weight In case vacuum'evaporation is employed, a slightly larger basic addition is desirableto compensate for the decreased loss of. hydrochloric acid. I

The solution is now concentrated either in At a concentration materiallyabove 70 Baum, and usually about 85 to95 Baum, depending upon theproportion of iron and the time and other conditions of evaporation, theiron separates quantatively and ultimately assumes the form offinely-divided or finely-granular anhydrous ferric oxid. The physicalcharacter of the precipitated oxid is such that it is very readilyseparated, either by filtration or by decantation, as compared withferric hydroxid. For ease of separation, it is desirable or necessaryagain. to dilute the solution, say to 50 or 55 Baum, at which dilution.the anhydrous ferric oxid settles rapidly and completely, and aperfectly clear and purified zinc chlorid solution if obtainable bysimple decantation. This solution may be re-concentrated to 70 Baum, oreven to dryness according to the use to which it is tobe applied. There-concentration is preferably carried out in copper or other suitablevessels to avoid further contamination by iron. I

In certain cases it is preferred to modify the procedure to the extentthat the original evaporation is continued beyond the point at which theferric compound undergoes dehydration, and "even to dryness or to suchdegree that the product assumes a solid form on cooling. The resultingproduct," in which the anhydrous ferric oxid .is intimately commingledwith zinc chlorid, is well adapted for storage or shipment. At anysubsequent time orplace it may be dissolved in water and filtered ordecanted at a dilution suitable for these operations, being subsequentlyre-concentrated if desired under conditions preventing furthercontamination by iron as above described.

sulfate of iron,

The process may serve also for recovering the values from the so-calledslimes produced in the puring of hard or vulcanized fiber, and in otherstages of the manufacture. These slimes consist chiefly of basiccompounds of zinc and ferric hydroxid or basic ferric salts, and may beintroduced directly into the zinc chlorid solution, prior to theevaporation, together with such further additions either of ferric saltsor compounds or of basic zinc salts or compounds as may be required toprovide the proper conditions, as above set forth, for the recovery ofiron as ferric oxid.

In case the ori inal solution ,contains some the purified chloridsolution will of course contain a corresponding proportion of zincsulfate, which is however not objectionable for certain purposes.

he expression hydrated ferric com pound is herein employed. as includingdissolved ferric salts, as well as hydrated oxycompounds, such as ferrichydroxid, basic ferric salts, etc.

It is to be understood that, as in the case of most chemical reactions,time, temperature and concentration -are, within proper limits, to beregarded as mutually convertible factors, so that the invention is notlimited to the specific conditions above set forth by way ofillustration.

I claim I 1. The method of dehydrating ferric compounds, which consistsin acting thereon with a concentrated solution of zinc chlorid.

2. The method which consists in reacting with a concentrated solution ofzinc chlorid sists in concentrating a zinc upon a dissolved ferric salt,in presence of a precipitant for iron, thereby precipitating the iron asanhydrous ferric oxid. v

8. The method of purifying zinc chlorid solutions containing ferriccompounds, which consists in concentratlng said solutions until 5. Themethod of treating zinc chlorid.

into anhydrous ferric solutions containingdissolved ferric salts,

the iron being in excess of one per, centfof the 'zinc, which consistsin introducing into said solutions a precipitant foriron, andconcentrating the solution until the iron is converted into anhydrousferric oxid.

6. The method oftreating zinc chlorid so-' lutions containing dissolvedferric salts, which consists in introducing thereinto a basic Zinccompound/and concentrating said solution until the iron is convertedinto anhydrous ferric oxid. 7

7. The method of treating zinc chlorid solutions containing dissolvedferric salts, which consists in introducing thereinto oxid of zinc, andconcentrating the iron is converted into anhydrous ferric oXid.

8. The method of preparing zinc chlorid solutions free from iron,

said solution until which consists in taining a hydrated ferric andseparating the ferric oxid from the diluted solution. Y

9. The method of preparing zinc chlorid solutions free from iron, whichconsists in concentrating a zinc chlorid solution containing a hydratedferric compound until the iron is converted into anhydrous ferric oXid,then adding water and separating the ferric oxid from the dilutedsolution and finally evaporating the purified solution.

10. The method of treating ferruginous zinc chlorid solutions to obtaincommercially pure zinc chlorid, which consists in adding to suchsolution a precipitant for iron in proportion somewhat less than thechemical equivalent of the evaporating the resulting liquor until theiron is converted into anhydrous ferric oxid.

11. In a method of preparing zinc chlorid solutions free from iron, thestep which conchlorid solution containing a hydrated ferric compounduntil ferric iron present, and

compounduntil the ron is converted into anhydrous ferric oxid, thenadding water the iron is converted into anhydrous ferric oXid, andcontinuing the evaporation until the product'assumes a solid conditionupon cooling. v

12. In a method of preparing zinc chlorid -cipitant for iron until theiron is converted solutions free from iron, the step which con- Intestimony whereof I afiix my signature sists in concentrating a zinechlorid solution in presence of two witnesses. v containing a dissolvedferric salt'and a pre- STANLEY HERBERT MWTON.

into anhydrous ferric oxid and continuing Witnesses: the evaporationuntil the product assumes a. CHARLES ALMY JL, solid condltion uponeoollng. W. J. ROBINSON.

